I am about to make some lager and I am able to get the primary fermentation temp in the correct range, but since it is very cold in my area the attic is the only place that I can get good lagering temps, but I know that it's a bit to cold and don't want my precious wort to freeze. I plan on doing lagering in a 5gal glass carboy. Does anyone know if towels or blankets will do the trick or do you have some other suggestions?

Although blankets may work, I found that an enormous picnic cooler (which I picked up at Costco for $40) worked well. Standing on its end, the cooler is big enough for me to fit a 6.5 gal carboy in, and still have room for a small shelf at the top on which I place a liter soda bottle that's been filled almost to the top with water and frozen. You may not need the ice bottle, but the cooler will work very well at slowing down any temperature changes.

That is exactly what I do to lager and it works like a charm. I use it in the warmer months also, the only difference is I must change the frozen water bottles every other day. I bought my cooler from Sears when they put summer items on sale....I paid $4 for mine, sure as hell beats buyin a fridge:)

I have the opposite problem, in that I have to keep my beer cool as it is always too hot for fermentation. A tip I got was to put a timer switch on your fridge, instead of spending big bucks on a new thermostat, I find I can achieve a good brew out temp by only having my fridge run for 4hrs a day, this also saves me money. Maybe you could do the same but with a heater belt or pad. I've never used one myself so i cant vouch for their efficiency, but with a little experimentation you could probably keep your lager just above freezing. I found this to be an excellent money saving tip for anyone who uses a fridge to brew out.

Rememeber that towels and blankets are only "insulators". Insulators help slow two bodies from exchanging heat/cold and reduce heat/cold transfer by wind, etc.

Insulators will only slow the rate in which your beer acclimates to the temperature of your attic.

Much of the heat in your house is lost through the attic. Perhaps you can utilize this! How about findind a spot above a particularly warm room, or beside a chimney. By building a small insulated box which allows the heat into it, and placing the batch in here you may have good results (i.e a bottomless box over a "hot spot", or a box missing one side that can be placed tight against an active chimney).
I also live in a cold climate, but I am lucky enough to have a springhouse on my property. This stone shed is partially underground, which prevents freezing. When it is very cold, I run a 100W light to produce enough heat in the shed to prevent freezing. You may also use a light for a heat source, but be careful not to design a fire hazard.